I have a 91 4.0L 5spd with a possible misfire or perhaps bad injector. I have replaced fuel filter, ign coil, wires, plugs, crank position sensor. And it still has the issue. Acts as if I am lugging it from 1800-2500+ rpm. I do idle high once warmed up. Like 1100rpm. My next guess is a or several bad injectors. Or perhaps the maf sensor is toast. Any help would be appreciated.